1. By: David Gitz, EE, Electrical/Programming Team Mentor FRC #1208
Drive Systems
By: David Gitz, EE, Electrical/Programming Team Mentor FRC #1208

2. Audience:
Programming Team Members
Electrical Team Members

3. Topics Wheels 2WD/4WD 6WD/West Coast Track Holonomic/Mecanum
Crab/Swerve

4. Wheels [2] Swivel Caster Ball Caster KoP Wheel Plaction Wheel
Omni-Wheel
Mecanum Wheel

5. Configurations [3] 2WD 4WD 6WD Omni/Mecanum simple rear wheel drive
front wheel drive
simple
all wheel drive
simple
center drive
6 wheel
drive
tracked drive
swerve/ crab drive
other?
Omni/Mecanum

6. 2 Wheel Drive The Good The Bad Cheap; Kitbot is 2WD
Very simple to build
The Bad
Easily spins out
Difficulty with inclines
Loses traction when drive wheels leave floor

7. 4 Wheel Drive The Good The Bad More easily controlled
Pretty simple to build
Better traction
The Bad
Turning in place is more difficult
Compromise between stability and maneuverability

8. 6WD/West Coast [3]
Typically, one wheel is offset from the others to minimize resistance to turning
Rocking creates two 4WD systems, effectively
Typical offset is 1/8” – ¼”
Rock isn’t too bad at edges of robot footprint, but can be significant at the end of long arms and appendages
One or two sets of omniwheels can be substituted for offset wheels.

9. Tracked [3] Pushing power increased Mechanically more complicated
Need to have adequate track tension
Throwing a track and/or breaking one can be easy and very hard to fix
Slower, much more power intensive
Applications
HEAVY duty pushing
Climbing

10. Omni/Mecanum Mechanically as complicated as a 4WD System
A lot of times can substitute normal wheels for Omni/Mecanum in tight situations.
Less pushing power, more maneuverable
Control can be more complicated (especially with Mecanum)
More parts that can break

11. Crab/Swerve [3] Extremely mechanically and program complex
Lots of parts to make/buy/fix
Highly maneuverable
Requires (normally) precise engineering
Takes up a lot of space, uses a lot of motors
Pure 4-Crab: 5
Pure 4-Swerve: 8!

12. Other Information Steering vs. Drive Systems
In FRC, there are no “Tank” Drive Systems. There is Tank Steering and Track Drive Systems. These terms are NOT interchangeable.
Tank Steering:
Uses 2 Joysticks, Left Joystick controls speed of Left motors, Right Joystick controls speed of Right motors.
Arcade Steering:
Uses 1 Joystick, controls speed of Left and Right motors together.

13. References
Drivetrain_Fundamentals_v2.1
FRC_Drive_Train_Design_and_Implementation

14. Questions?

15. Homework
1. Describe the Drive Train FRC Team #1208 (us…) used in the FRC 2010 Competition.
2. Name 1 advantage and 1 disadvantage of using a Meccanum Drive System.
3. What is the difference between Tank Steering and a Track Drive System?